Resolution, noise and sensitivity
Given the higher pixel count of the EOS 550D, it’s not really a bolt from the blue to discover that it can resolve detail further along our resolution test chart than the D90. However, with images of more photogenic subjects the difference is not immediately obvious.
At 300ppi, images from both cameras look very good, and when the resolution of the images from the D90 is dropped to make prints that match the physical dimensions of a print made from an EOS 550D file at 300ppi, in many situations there is very little difference. When images are sized to make A2 prints it is possible to see a little more fine detail in some of the results from the Canon camera, you have to look for it and the difference doesn’t leap out at you, but it is there.
It is perhaps a little more surprising to find that the Canon camera doesn’t produce dramatically noisier images than the D90. In fact, when their high-sensitivity noise-reduction systems are set to their default values, the Canon camera’s JPEG files have lower noise levels.
As usual, the best results from both cameras are produced from raw files when the level of chroma and luminance noise reduction can be controlled to find the best compromise between visible noise and loss of detail.
Image: The difference in the level of detail isn’t immediately apparent in these two shots, but when they are magnified it is possible to see a little more fine detail in the Canon image
These images show 72ppi sections of images of a resolution chart, captured using matching 105mm macro lenses. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
